draft-ietf-6tisch-enrollment-enhanced-beacon-01.txt   draft-ietf-6tisch-enrollment-enhanced-beacon-02.txt 
6lo Working Group D. Dujovne 6lo Working Group D. Dujovne
Internet-Draft Universidad Diego Portales Internet-Draft Universidad Diego Portales
Intended status: Standards Track M. Richardson Intended status: Standards Track M. Richardson
Expires: July 21, 2019 Sandelman Software Works Expires: September 26, 2019 Sandelman Software Works
January 17, 2019 March 25, 2019
IEEE802.15.4 Informational Element encapsulation of 6tisch Join and IEEE802.15.4 Informational Element encapsulation of 6tisch Join and
Enrollment Information Enrollment Information
draft-ietf-6tisch-enrollment-enhanced-beacon-01 draft-ietf-6tisch-enrollment-enhanced-beacon-02
Abstract Abstract
In TSCH mode of IEEE802.15.4, as described by [RFC8180], In TSCH mode of IEEE802.15.4, as described by [RFC8180],
opportunities for broadcasts are limited to specific times and opportunities for broadcasts are limited to specific times and
specific channels. Nodes in a TSCH network typically frequently send specific channels. Nodes in a TSCH network typically frequently send
Enhanced Beacon (EB) frames to announce the presence of the network. Enhanced Beacon (EB) frames to announce the presence of the network.
This document provides a mechanism by which small details critical This document provides a mechanism by which small details critical
for new nodes (pledges) and long sleeping nodes may be carried within for new nodes (pledges) and long sleeping nodes may be carried within
the Enhanced Beacon. the Enhanced Beacon.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 21, 2019. This Internet-Draft will expire on September 26, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 3 1.2. Layer-2 Synchronization . . . . . . . . . . . . . . . . . 3
1.3. Layer-3 synchronization IPv6 Router solicitations and 1.3. Layer-3 synchronization IPv6 Router solicitations and
advertisements . . . . . . . . . . . . . . . . . . . . . 3 advertisements . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 4 2. Protocol Definition . . . . . . . . . . . . . . . . . . . . . 4
2.1. Protocol Example . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Change history . . . . . . . . . . . . . . . . . . . 8 Appendix A. Change history . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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how they could be compressed. how they could be compressed.
1.1. Terminology 1.1. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
[RFC2119] and indicate requirement levels for compliant STuPiD [RFC2119] and indicate requirement levels for compliant STuPiD
implementations. implementations.
Other terminology can be found in [I-D.ietf-6tisch-architecture] in
section 2.1.
1.2. Layer-2 Synchronization 1.2. Layer-2 Synchronization
As explained in section 6 of [RFC8180], the Enhanced Beacon has a As explained in section 6 of [RFC8180], the Enhanced Beacon has a
number of purposes: synchronization of ASN and Join Metric, timeslot number of purposes: synchronization of ASN and Join Metric, timeslot
template identifier, the channel hopping sequence identifier, TSCH template identifier, the channel hopping sequence identifier, TSCH
SlotFrame and Link IE. SlotFrame and Link IE.
The Enhanced Beacon (EB) is used by nodes already part of a TSCH The Enhanced Beacon (EB) is used by nodes already part of a TSCH
network to annouce its existance. Receiving an EB allows a Joining network to annouce its existance. Receiving an EB allows a Joining
Node (pledge) to learn about the network and synchronize to it. The Node (pledge) to learn about the network and synchronize to it. The
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to re-synchronize [RFC7554]. to re-synchronize [RFC7554].
There are a limited number of timeslots designated as a broadcast There are a limited number of timeslots designated as a broadcast
slot by each router. These slots are rare, and with 10ms slots, with slot by each router. These slots are rare, and with 10ms slots, with
a slot-frame length of 100, there may be only 1 slot/s for the a slot-frame length of 100, there may be only 1 slot/s for the
beacon. beacon.
1.3. Layer-3 synchronization IPv6 Router solicitations and 1.3. Layer-3 synchronization IPv6 Router solicitations and
advertisements advertisements
At layer 3, [RFC2461] defines a mechanism by which nodes learn about At layer 3, [RFC4861] defines a mechanism by which nodes learn about
routers by listening for multicasted Router Advertisements (RA). If routers by listening for multicasted Router Advertisements (RA). If
no RA is heard within a set time, then a Router Solicitation (RS) may no RA is heard within a set time, then a Router Solicitation (RS) may
be multicast, to which an RA will be received, usually unicast. be multicast, to which an RA will be received, usually unicast.
Although [RFC6775] reduces the amount of multicast necessary to do Although [RFC6775] reduces the amount of multicast necessary to do
address resolution via Neighbor Solicitation messages, it still address resolution via Neighbor Solicitation messages, it still
requires multicast of either RAs or RS. This is an expensive requires multicast of either RAs or RS. This is an expensive
operation for two reasons: there are few multicast timeslots for operation for two reasons: there are few multicast timeslots for
unsolicited RAs; if a pledge node does not hear an RA, and decides to unsolicited RAs; if a pledge node does not hear an RA, and decides to
send a RS (consuming a broadcast aloha slot with unencrypted send a RS (consuming a broadcast aloha slot with unencrypted
traffic), unicast RS may be sent in response. XXX traffic), unicast RS may be sent in response.
This is a particularly acute issue for the join process for the This is a particularly acute issue for the join process for the
following reasons: following reasons:
1. use of a multicast slot by even a non-malicious unauthenticated 1. use of a multicast slot by even a non-malicious unauthenticated
node for a Router Solicitation may overwhelm that time slot. node for a Router Solicitation may overwhelm that time slot.
2. it may require many seconds of on-time before a new pledge hears 2. it may require many seconds of on-time before a new pledge hears
a Router Soliciation that it can use. a Router Soliciation that it can use.
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+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+ +
| network ID | | network ID |
+ variable length, up to 16 bytes + + variable length, up to 16 bytes +
~ ~ ~ ~
+ + + +
| | | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
proxy priority the proxy prority value contains a number from 0 to proxy priority Lower value indicates willing to act as a Join Proxy
0x7f. Lower numbers are considered to be a higher preference. A as described in [I-D.ietf-6tisch-minimal-security]. Values range
priority of 0x7f indicates that the announcer should never be 0 (most willing) to 0x7e (least willing). A priority of 0x7f
considered as a viable enrollment proxy. Lower value indicates indicates that the announcer should never be considered as a
willing to act as a Join Proxy as described in viable enrollment proxy. Only unenrolled pledges look at this
[I-D.ietf-6tisch-minimal-security]. Only unenrolled pledges look value.
at this value.
pan priority the pan priority is a value set by the DODAG root to pan priority the pan priority is a value set by the DODAG root to
indicate the relative priority of this LLN compared to those with indicate the relative priority of this LLN compared to those with
different PANIDs. This value may be used as part of the different PANIDs. This value may be used as part of the
enrollment priority, but typically is used by devices which have enrollment priority, but typically is used by devices which have
already enrolled, and need to determine which PAN to pick. already enrolled, and need to determine which PAN to pick.
Unenrolled pledges MAY consider this value when selecting a PAN to Unenrolled pledges MAY consider this value when selecting a PAN to
join. Enrolled devices MAY consider this value when looking for join. Enrolled devices MAY consider this value when looking for
an eligible parent device. an eligible parent device.
rank priority the rank "priority" is set by the 6LR which sent the rank priority the rank "priority" is set by the 6LR which sent the
beacon and is an indication of how willing this 6LR is to serve as beacon and is an indication of how willing this 6LR is to serve as
an RPL parent within a particular network ID. This is a local an RPL parent within a particular network ID. This is a local
value to be determined in other work. It might be calculated from value to be determined in other work. It might be calculated from
RPL rank, and it may include some modifications based upon current RPL rank, and it may include some modifications based upon current
number of children, or number of neighbor cache entries available. number of children, or number of neighbor cache entries available.
This value MUST be ignored by pledges, it is for enrolled devices This value MUST be ignored by pledges, it is for enrolled devices
only. only.
R the Router Advertisement flag is set if the sending node will act R the Router Advertisement R-flag is set if the sending node will
as a Router for host-only nodes that need addressing via unicast act as a Router for host-only nodes that need addressing via
Router Solicitation messages. unicast Router Solicitation messages.
P if the Proxy Address bit is set, then the lower 64-bits of the P if the Proxy Address P-flag is set, then the lower 64-bits of the
Join Proxy's Link Layer address follows the network ID. If the Join Proxy's Link Layer address follows the network ID. If the
Proxy Address bit is not set, then the Link Layer address of the Proxy Address bit is not set, then the Link Layer address of the
Join Proxy is identical to the Layer-2 8-byte address used to Join Proxy is identical to the Layer-2 8-byte address used to
originate this enhanced beacon. In either case, the layer-2 originate this enhanced beacon. In either case, the layer-2
address of any IPv6 traffic to the originator of this beacon may address of any IPv6 traffic to the originator of this beacon may
use the layer-2 address which was used to originate the beacon. use the layer-2 address which was used to originate the beacon.
join-proxy lower-64 if the P bit is set, then 64 bits (8 bytes) of join-proxy lower-64 if the P-flag bit is set, then 64 bits (8 bytes)
address are present. The Link Layer address of the Join Proxy is of address are present. The Link Local address of the Join Proxy
fe80 (as for any Link Layer address), and the bits given in this is fe80 (as for any Link Local address), and the bits given in
field. this field.
network ID this is an variable length field, up to 16-bytes in size network ID this is an variable length field, up to 16-bytes in size
that uniquely identifies this network, potentially among many that uniquely identifies this network, potentially among many
networks that are operating in the same frequencies in overlapping networks that are operating in the same frequencies in overlapping
physical space. The length of this field can be calculated as physical space. The length of this field can be calculated as
being whatever is left in the Information Element. being whatever is left in the Information Element.
In a 6tisch network, where RPL is used as the mesh routing protocol, In a 6tisch network, where RPL [RFC6550] is used as the mesh routing
the network ID can be constructed from a SHA256 hash of the prefix protocol, the network ID can be constructed from a SHA256 hash of the
(/64) of the network. That is just a suggestion for a default value. prefix (/64) of the network. That is just a suggestion for a default
In some LLNs where multiple PANIDs may lead to the same management value. In some LLNs where multiple PANIDs may lead to the same
device (the JRC), then a common value that is the same across all management device (the JRC), then a common value that is the same
PANs MUST be configured. across all PANs MUST be configured.
2.1. Protocol Example
Here will be three examples of processing.
3. Security Considerations 3. Security Considerations
All of the contents of this Information Element are sent in the All of the contents of this Information Element are sent in the
clear. The containing Enhanced Beacon is not encrypted. clear. The containing Enhanced Beacon is not encrypted.
The Enhanced Beagon is authenticated at the layer-2 level using The Enhanced Beagon is authenticated at the layer-2 level using
802.15.4 mechanisms using the network-wide keying material. Nodes 802.15.4 mechanisms using the network-wide keying material. Nodes
which are enrolled will have the network-wide keying material and can which are enrolled will have the network-wide keying material and can
validate the beacon. validate the beacon.
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Thomas Watteyne provided extensive editorial comments on the Thomas Watteyne provided extensive editorial comments on the
document. document.
7. References 7. References
7.1. Normative References 7.1. Normative References
[I-D.ietf-6tisch-architecture] [I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-19 (work of IEEE 802.15.4", draft-ietf-6tisch-architecture-20 (work
in progress), December 2018. in progress), March 2019.
[I-D.ietf-6tisch-minimal-security] [I-D.ietf-6tisch-minimal-security]
Vucinic, M., Simon, J., Pister, K., and M. Richardson, Vucinic, M., Simon, J., Pister, K., and M. Richardson,
"Minimal Security Framework for 6TiSCH", draft-ietf- "Minimal Security Framework for 6TiSCH", draft-ietf-
6tisch-minimal-security-09 (work in progress), November 6tisch-minimal-security-09 (work in progress), November
2018. 2018.
[ieee802154] [ieee802154]
IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low- IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low-
Rate Wireless Personal Area Networks (WPANs)", 2015, Rate Wireless Personal Area Networks (WPANs)", 2015,
<http://standards.ieee.org/findstds/ <http://standards.ieee.org/findstds/
standard/802.15.4-2015.html>. standard/802.15.4-2015.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
Discovery for IP Version 6 (IPv6)", RFC 2461, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC2461, December 1998, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc2461>. <https://www.rfc-editor.org/info/rfc4861>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012, RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554, Internet of Things (IoT): Problem Statement", RFC 7554,
skipping to change at page 7, line 44 skipping to change at page 7, line 38
Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May
2017, <https://www.rfc-editor.org/info/rfc8137>. 2017, <https://www.rfc-editor.org/info/rfc8137>.
7.2. Informative References 7.2. Informative References
[I-D.ietf-6tisch-dtsecurity-secure-join] [I-D.ietf-6tisch-dtsecurity-secure-join]
Richardson, M., "6tisch Secure Join protocol", draft-ietf- Richardson, M., "6tisch Secure Join protocol", draft-ietf-
6tisch-dtsecurity-secure-join-01 (work in progress), 6tisch-dtsecurity-secure-join-01 (work in progress),
February 2017. February 2017.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>.
[RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal [RFC8180] Vilajosana, X., Ed., Pister, K., and T. Watteyne, "Minimal
IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH) IPv6 over the TSCH Mode of IEEE 802.15.4e (6TiSCH)
Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180, Configuration", BCP 210, RFC 8180, DOI 10.17487/RFC8180,
May 2017, <https://www.rfc-editor.org/info/rfc8180>. May 2017, <https://www.rfc-editor.org/info/rfc8180>.
Appendix A. Change history Appendix A. Change history
The rank priority was expanded to 2 bytes. The rank priority was expanded to 2 bytes.
00: The extension was originally for the use of Pledges only during 00: The extension was originally for the use of Pledges only during
 End of changes. 15 change blocks. 
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